• Atrial Fibrillation/Flutter Patients Undergoing Cardioversion at Higher Risk of Left Atrial Thrombus – Database Analysis

    TEE could be ‘reasonable approach’ to minimize thromboembolic complications, study says

    Atrial fibrillation (AF) and atrial flutter (AFL) patients undergoing cardioversion versus ablation were found to be at higher risk of left atrial (LA) thrombus, according to a new database analysis.

    Other risk factors included older age, congestive heart failure and hypertension, according to the study, published online Monday and in the June 15 issue of the Journal of the American College of Cardiology.

    Transesophageal echocardiogram (TEE) imaging could be “a reasonable approach” to minimize post-procedural thromboembolic complications for these patients, the study authors, led by Antony Lurie, BMSc, from the Population Health Research Institute and University of Western Ontario noted.

    LA thrombus is contraindicated to cardioversion and catheter ablation in AF and AFL patients because the procedures may dislodge pre-existing thrombi, resulting in cardioembolic stroke.

    Pre-procedural anticoagulation, therefore, is routinely used to minimize associated thromboembolic events, the researchers said. For those with AF/AFL who have been taking therapeutic oral anticoagulation for at least 3 weeks pre-procedure, however, current guidelines do not recommend TEE before cardioversion.

    The use of TEE before catheter ablation for AF remains “variable” and “inconsistent” with cardioversion guidelines, the authors added. A recent consensus document recommends that TEE is reasonable if the patient is in AF at the time of ablation, regardless of anticoagulation status, but also suggests that cardioversion guidelines be followed in those presenting for AF ablation otherwise.

    Together with the significant uptick in direct oral anticoagulant (DOAC) use in recent years, this inconsistency suggests that the need for pre-procedural TEE to detect LA thrombus should be re-evaluated, the authors said.

    Yet the prevalence of LA thrombus in AF and AFL patients on guideline-directed anticoagulation – knowledge that could inform TEE use – is not well defined in large datasets, they stressed.

    The researchers, therefore, set out to systematically search the EMBASE, MEDLINE and CENTRAL study databases from inception to July 2020 for studies reporting on LA thrombus prevalence in AF/AFL patients undergoing TEE following at least 3 weeks of continuous oral anticoagulation with either vitamin K agonists (VKAs) or DOACs.

    The authors found 35 articles describing 14,653 patients to be included in meta analyses. All studies were observational, 10 were prospective, and 25 were retrospective. Because the included studies consisted of clinically heterogenous populations, all analyses were performed using random effects models.

    The mean-weighted LA thrombus prevalence was 2.73% (95% confidence interval [CI]: 1.95% to 3.80%).

    In a bid to identify those at higher risk in which the diagnostic yield of TEE may be greater, prevalence of LA thrombus was also assessed by oral anticoagulant type, AF pattern, TEE indication, and CHADS2 (congestive heart failure, hypertension, age ≥75, diabetes and stroke)/CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75, diabetes, stroke, vascular disease, age 65 to 74 and female sex) score.

    Despite current guidelines, those undergoing cardioversion had higher prevalence of LA thrombus than those undergoing ablation (5.55%, [95% CI: 3.15% to 9.58%] vs. 1.65% [95% CI: 1.07% to 2.53%]; p < 0.001).

    CHA2DS2-VASc scores of 3 or more had higher prevalence compared with scores of 2 or less (6.31% [95% CI: 3.72% to 10.49%] vs. 1.06% [95% CI: 0.45% to 2.49%]; p < 0.001).

    Patients with non-paroxysmal AF/AFL were also found to be at higher risk, with a fourfold higher LA thrombus prevalence compared with paroxysmal patients (respectively, 4.81% [95% CI: 3.35% to 6.86%] vs. 1.03% [95% CI: 0.52% to 2.03%]; p < 0.001).

    There was little difference between the kind of anticoagulant given and LA thrombus prevalence (VKA 2.80% [95% CI: 1.86% to 4.21%] vs. DOACs 3.12% [95% CI: 1.92% to 5.03%]; p = 0.674).

    “TEE imaging in select patients at an elevated risk of LA thrombus, despite anticoagulation status, may be a reasonable approach to minimize the risk of thromboembolic complications following cardioversion or catheter ablation,” the researchers concluded.

    “Fortunately, continued oral anticoagulation already yields low peri-procedural stroke rates,” University Heart & Vascular Center Hamburg and the German Centre of Cardiovascular Research’s Paulus Kirchhof, MD, and Christoph Sinning, MD, and added in an accompanying editorial. (Kirchhof is also of the University of Birmingham.)

    However, they agreed that a risk-based use of TEE imaging in anticoagulated patients could enable further improvement in the safe delivery of rhythm-control interventions in patients with AF.



    Lurie A, Wang J, Hinnegan KJ, et al. Prevalence of Left Atrial Thrombus in Anticoagulated Patients With Atrial Fibrillation. J Am Coll Cardiol 2021;77:2875-86.

    Kirchhof P, Sinning C. Thrombus or No Thrombus: Is That the Embolic Question? J Am Coll Cardiol 2021;77:2887-9.

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